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Subject[tip:x86/asm] x86/ptrace: Remove checks for TIF_IA32 when changing CS and SS
Commit-ID:  08571f1ae327bfb631cb7171bde5ea605df626c6
Gitweb: http://git.kernel.org/tip/08571f1ae327bfb631cb7171bde5ea605df626c6
Author: Andy Lutomirski <luto@amacapital.net>
AuthorDate: Tue, 24 Feb 2015 16:01:38 -0800
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 25 Feb 2015 08:27:49 +0100

x86/ptrace: Remove checks for TIF_IA32 when changing CS and SS

The ability for modified CS and/or SS to be useful has nothing
to do with TIF_IA32. Similarly, if there's an exploit involving
changing CS or SS, it's exploitable with or without a TIF_IA32
check.

So just delete the check.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Link: http://lkml.kernel.org/r/71c7ab36456855d11ae07edd4945a7dfe80f9915.1424822291.git.luto@amacapital.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/kernel/ptrace.c | 10 ++--------
1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index e510618..1e12581 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -364,18 +364,12 @@ static int set_segment_reg(struct task_struct *task,
case offsetof(struct user_regs_struct,cs):
if (unlikely(value == 0))
return -EIO;
-#ifdef CONFIG_IA32_EMULATION
- if (test_tsk_thread_flag(task, TIF_IA32))
- task_pt_regs(task)->cs = value;
-#endif
+ task_pt_regs(task)->cs = value;
break;
case offsetof(struct user_regs_struct,ss):
if (unlikely(value == 0))
return -EIO;
-#ifdef CONFIG_IA32_EMULATION
- if (test_tsk_thread_flag(task, TIF_IA32))
- task_pt_regs(task)->ss = value;
-#endif
+ task_pt_regs(task)->ss = value;
break;
}


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